Development of a sensing technology for edible oil identification by using near infrared InGaAsP DFB laser diodes

This paper describes an oil identification experimental system developed for enhanced food safety and testing. First, we investigated the absorption properties of oils, that they were six edible and one inedible, using a commercial spectrometer. Results showed the possibility of identifying oils by comparing absorbance at the max (1727 nm) and four adjacent wavelengths (1750, 1713, 1685 and 1657 nm). Then we developed an experiment system capable of performing the investigation of the absorption properties based on the result of examination with a spectrophotometer. The experimental system consisted of laser diode (LD) light sources with 1713 nm and 1727 nm, one photo diode detector, and six optical cells of different optical path length. Absorbance of a salad oil measured by the system successfully reflected the Lambert-Beer law that depended on the wavelength and the optical path length. The system stability was within ±0.2 %. These results show a possibility of a sensor-type oil identification system that is an improvement of the experimental system.